Gaia cleared hundreds of thousands of double stars in the Milky Way

Monday, June 13th, the latest Gaia catalog was released, along with many new disclosures. Among them, an astronomical amount of binary systems is detailed in the galaxy, showing their much higher number than expected.

this stars social! Or at least, they are born and spend their lives surrounded by other stars for a third of their time. This was revealed by the latest data catalog Gaia Version 3, which listed more than a billion additional objects. Among them, 813,000 double star Gaia offers: two stars orbit around each other. That’s a high number, especially when compared to the 300,000 listed so far! In the long run, the mission aims to map our world precisely. Galaxy, Milky Way.

This animation shows the motions of binary stars whose orbits are determined by Gaia, projected into the sky. Each ellipse corresponds to one of 335 systems with periods of less than 1,000 days, located within 50 parsecs (163 light-years). © ESA, Gaia, DPAC

Orbits are represented to scale in this animation and classified by increasing distance from the orbits. Sun from top left to bottom right. The white horizontal line in the lower right indicates an arc size of 10 milliseconds. this colour It roughly matches the source color determined by Gaia, with purple/blue indicating hot stars, and white dwarfssimilar to green/yellow pointing stars Sun and red indicates cold, faint stars mass. this movements equals 1,000 days, duration Observation conducted by Gaïa for this last observation campaign.

It is the influence of one star on another that makes it possible to identify them.

To obtain all these details, the researchers used various instruments on the satellite that made it possible to characterize each targeted object.

When several stars are in the same orbit, they affect each other: this allows them to be identified. viewed by an outside observer. multiple systems It has a unique signature. To begin with, their orbits seem far from that of a lone system.

When two orbiting objects are far enough apart, their oscillations in the sky are detected by astrometry, which consists of measuring the position and motion of stars. In this particular case, one of the two stars is impossible to observe, but the farthest motion is enough to detect its existence. © ESA, Gaia, DPAC

But be careful, if the system is too far from the observer, two stars will appear merged. In the case of a short orbit of only a few days, two stars nearby: their proximity gives them a high probability of being observed, thanks to a later drop. brightness characteristic when passing one in front of the other. Also, for systems with the same short orbits, speed detectable by radial spectrometry : examining spectrum light emitted by the source. At the other extreme, very distant multiple systems are detected by small dips in the brightness of faint stars.

Here, spectrometry is used to follow the movement of lines in the light spectrum of stars: if a source is approaching, then periodically receding, as in binary systems, its radial velocity also changes periodically. The binaries observed by this method are called spectroscopic binaries. © ESA, Gaia, DPAC

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